According to tests run by Computerworld , the Chrome beta, which Google launched yesterday, is the second fastest of the major Windows browsers . Chrome 5.0.375.29 also renders JavaScript about 17% faster than Chrome 4.1.249.1064, the current "stable" edition. Google simultaneously supports three lines of Chrome, ranked in descending order of stability as its stable, beta and dev channels.

But Opera Software's Opera 10.53 remains the king of JavaScript, with benchmark scores about 16% faster than those by the newest Chrome beta. The Norwegian browser first took the crown last February, when the browser debuted a new JavaScript engine dubbed Carakan, and surged past Apple 's Safari for Windows and Chrome, the former No. 1 and No. 2 browsers.

Other browsers held their usual spots in the latest round of tests. Safari 4.0.5 was only slightly slower than the stable edition of Chrome, and so held down the No. 3 spot, while Mozilla's Firefox 3.6.3 was just over half as fast as Safari and Chrome. Microsoft 's Internet Explorer 8 (IE8), as usual, brought up the rear as the slowest of the five browsers in JavaScript rendering: IE8 was more than 12 times slower than Opera 10.53.

Computerworld ran the SunSpider JavaScript benchmark suite in Windows XP Professional Service Pack 3 (SP3) three times for each browser, then averaged the scores to arrive at the final rankings.

On Tuesday, Google said the newest Chrome beta was 35% faster on the SunSpider tests than the beta of its earlier version 4.0 for Windows. Computerworld wasn't able to verify that claim -- Google updates its browser automatically, without user intervention, making it difficult to keep Chrome on a specific version -- but also tested the newest beta against the previous beta, marked as Chrome 5.0.342.8.

The update boosted Chrome's speed by 6% over that beta, which Google released in late March.

Other additions include support for several HTML5 features, such as geo-location and drag-and-drop; synchronization of browser settings to effectively "clone" Chrome on multiple machines; and the ability to use extensions when working in Chrome's "Incognito" private browsing mode.

This beta also introduces the integration of Adobe's Flash Player to Chrome's beta channel.

Google debuted built-in Flash in developer builds at the end of March, when it announced a partnership with Adobe, and said it was packaging Flash with Chrome downloads and would silently update the often-patched media player using the browser's background mechanism.

The move, Adobe said at the time, would keep Chrome users safer since they wouldn't have to remember to update or deal with update notifications.